Extraction with gamma-butyrolactone



EXTRACTION WITH GAMlVIA-BUTYROLACTONE Paul N. Rylander, Newark, N.J.,asslgnor to Standard Oil Company, Chicago, 111., a corporation ofIndiana No Drawing. Appiication llecember 23,1957 Serial No. 704,508

6 Claims. (Cl. 260-450) The present invention relates to the extractionof oilsoluble, water-immiscible alcohols from normally liquidhydrocarbons, and particularly concerns the use of liquidgamma-butyrolactone as a selective solvent for this purpose.

An object of the present invention is to provide a method for removingdissolved water-immiscible alcohols from mixtures thereof with liquidhydrocarbons. Another object is to provide a method for removing suchalcohols from mixtures thereof with liquid hydrocarbons and organiccarbonyl compounds. A further object is to provide a method forrecovering valuable oil-soluble chemicals from the products ofhydrogenation of carbon monoxide in the presence of an iron catalyst.Other objects and advantages of the invention will be apparent from thedetailed description thereof.

It has been found that oil-soluble alcohols can be extracted from amixture of the alcohol jwith normally liquid hydrocarbons by employingliquid gamma-butyrolactone as the selective solvent. Mixtures such ascan not readily be separated by distillation due to the closeness of theboiling points of the hydrocarbon and alcohol or because of azeotropeformation are readily separated by extraction with liquidgamma-butyrolactone. The process is selective for extracting alcohols inpreference .to organic carbonyl compounds such as aldehydes and ketones,and improved selectivity can be obtained by scrubbing the extract(either during the extraction process or after separation of an extractphase).with a liquid hydrocarbon. Such liquid hydrocarbon is-one thatboils outside the boiling range of the components of the mixparticulartype of hydrocarbon present has no critical ture undergoing separation.The oil-soluble products obinvention is quite surprising. Its loweradjacent homolog, ,beta-propiolactone, cannot be practicably used as a-selective solvent where hydrocarbons are present because it isviolently reactive with substances containing active hydrogen whichsometimes induce polymerization of this lactone at an explosive rate.The next adjacent higher homolog of gamma-butyrolactone,vgamma-,valerolactone,

.is miscible at room temperature in all proportions with hydrocarbons.Delta-valerolactone condenses readily ,to form polyesters.Beta-butyrolactone is: unstable. It is rapidly and irreversiblyhydrolyzed.

The liquid gamma-butyrolactone can be used infth'e solvent extraction ofmixtures of normally liquid hydrocarbons and oil-soluble,water-immisciblealcohols. The

extract phase of gamma-butyrolactone is rich in extract ed bearing uponthe extraction process, and it may be an aromatic, cycloaliphatic oraliphatic hydrocarbon, e.g; parafiin, olefin, or mixtures of varioushydrocarbons. The mixture undergoing extraction may consist of a wideboiling range mixture of hydrocarbons and alcohols or a narrow boilingrange mixture. The present invention is particularly useful forseparating mixtures which cannot ordinarily be separated'by distillationdue to the the closeness of boiling points of the hydrocarbon andalcohol or because azeotropes are formed between the hydrocarbon andalcohol.

Chemical manufacturers often have mixtures of waterimmiscible,oil-soluble alcohols with normally liquid hydrocarbons. Such mixturesare formed during the oxidation of hydrocarbons such as paraflinicand/or olefinic hydrocarbons. They are also formed during thehydrogenation of carbon monoxide by the Fischer-Tropsch process and itsvarious modifications. As an example of this process, carbon monoxideand hydrogen are contacted with iron catalyst at a temperature betweenabout 450 to 750 F. and a pressure between about to 700 V p.s.i.g.Streams of water-soluble and oil-soluble chemicals are produced. Thewater-soluble alcohols may readily be recovered from the products bywater washing techniques, but the oil-soluble alcohols are difiicult'toremove from the hydrocarbons which are produced during the process. Theoil-soluble organic chemicals, which form a homogeneous solution in theliquid hydrocarbons, consist of carboxylic acids, alcohols, aldehydesand ke tones, and a small amount of esters. The composition of such astream is given in Industrial and Engineering Chemistry, volume 45,pages 359-362 (February 1953). The carboxylic acids may be removed fromthis hydrocarbon stream containing the oil-soluble chemicals byextracting with aqueous solutions of sodium carbonate, or by othertechniques. Thereafter the hydrocarbon stream of oil-soluble chemicalsmay be extracted With liquid gamma-butyrolactone to remove the alcoholsfrom the hydrocarbons. Either a wide boiling range portion of the theoil-soluble chemicals stream may be extracted, or a narrow boilingmixture may be extracted. This solvent is quite selective for extractingthe alcohol from the hydrocarbon. It has only slight effectiveness forextracting aldehydes and ketones from the hydrocarbons. Thus it may alsobe used to extract alcohols from aldehydes and/or ketones. p i

When it is desired to remove the maximum amount of the variousoxygenated hydrocarbons present in the hydrocarbon stream containingdissolved alcohols, carbonyl compounds, etc. from the Fischer-Tropschprocess or from similar streams from hydrocarbon oxidation process, thehydrocarbon oil containing the dissolved oil'- soluble oxygenatedhydrocarbons may be hydrogenated to convert aldehydes and ketonestherein to alcohols. Because alcohols are extracted by liquidgamma-butyrolatitone with highefiiciency, a more complete purificationof .the hydrocarbon is obtained during the solvent extraction step. Thisrenders the rafiinate hydrocarbon phase more suitable for subsequent usesuch as for deoxy'genation and conversion of the hydrocarbons togasoline con- .stituents. The hydrogenation may be carried out aPatented lviar. 29, 1960 of carbonyl groups are taught in the textReactions of Hydrocarbon, by H. Adkins, University of Wisconsin Press,1937, pages 8, 11.

In general, liquid-liquid extraction operations can be carried out withgamma-butyrolactone at temperatures between about -30 C. and about 200C., preferably at a temperature between about -20 C. and 50 C., e.g. 25C. The particular temperature used will depend upon the particularcharging stock, the so1vent:feed ratio, the number of extraction stages,the. degree of ex traction which is sought, the proportions of auxiliarysolvents or countersolvents (if any), etc.

The ratio of solvent to the charge mixture of hydrocarbons and alcoholundergoing separation, must be sufficient to exceed the solubility ofthe solvent in the charge stock in order to form two distinct liquidphases,

viz. a rafiinatephase of hydrocarbons containing little or no solvent,and an immiscible extract phase of solvent containing the alcohols asthe solute. Generally, between about 0.2 to volumes of solvent may beused per volume of the charge mixture which is to be separated. Equalvolumes of solvent and charge mixture constitute a very satisfactoryratio. To the solvent-may be added from 1 to 20% of water. The waterincreases the selectivity of the solvent for extracting alcohols. Watermay be introduced into the extraction zone together with the solvent, orit may be separately introduced into the extraction zone at a point awayfrom that at which the solvent is introduced. To increase theselectivity for removing alcohols in preference to hydrocarbons orcarbonyl compounds such as aldehydes and ketones, a hydrocarboncountersolvent may be used. This countersolvent is preferably one whichboils outside the boiling range of the charge mixture undergoingseparation and outside the boiling range of the solvent. In this way itcan be fractionated to separate it from the hydrocarbon rafiinate phaseand the extract phase (when any amounts are left in this latter phase).The countersolvent may be used during the extraction process byintroducing it into the extraction zone so that it scrubs the extractphase as it passes through the extraction zone. In this manner it scrubsout the carbonyl compounds and any minor amounts of hydrocarbons whichmay be ordinarily extracted from the charge mixture. Washing with thehydrocarbon countersolvent may also be carried out after the extractphase has been separated from the raffinate phase. In this manner theseparated extract phase may be scrubbed in a tower or other suitableequipment to remove the extracted carbonyl compounds and hydrocarbonsfrom the extract phase. The alcohols may then be recovered in goodpurity by distilling to separate them from the solvent. Other techniquesbesides distillation may be used to recover the alcohols from thesolvent, e.g. washing the extract phase with water to dissolve out thesolvent and then recovering the solvent from the water. Likewise, anydissolved solvent can be recovered from the rafiinate phase by washingwith water. The extraction process can be carried out in a batch,continuous or semicontinuous manner, and in one or more actual ortheoretical stages, employing contacting equipment such as hasheretofore been employed in the selective solvent refining art.

Certain solvent extractions were carried out which are illustrativeofthe present invention. A mixture of hydrocarbons and oil-solubleoxygenated compounds which was prepared by the hydrogenation of carbonmonoxide in the presence of an iron catalyst (modified Fischer- Tropschsprocess) was obtained. The carboxylic acids had been removed from thismixture, and the mixture had been fractionated to obtain the chargingstock employed in. the solvent extraction step. The fraction charged tothe solvent extraction step consisted of approximately 58.5 volumepercent C olefins, 11.0 volume percent saturated hydrocarbons, 7.5volume percent aromatics, and 23.0 volume percent oxygen-containinghydrocarbons. The saturated hydrocarbons, aromatics, andoxygen-containing hydrocarbons boiled within the same range as the C1041olefins. The alcohols, which were primarily C alcohols, comprised about11.8% of the mixture charged to extraction, the aldehydes comprisedabout 8.0% of the mixture charged to extraction, and the remaining 23%consisted primarily of ketones with a minor amount of other oxygenatedhydrocarbons. ml. of the above defined mixture was shaken with 100ml..of gamma-butyrolactone at 25 C. A raflinate layer of 76 ml. and anextract layer of 124 ml. were thereafter separated. Analysis of therafiinate, after washing with water to remove any dissolved solvent,indicated that 73.7% of the alcohol had been extracted therefrom.Analysis of the raflinate indicated that 51.4% of the totaloxygen-containing hydrocarbons (alcohols, aldehydes, ketones) had beenextracted. This indicates that alcohols were removed from thehydrocarbon raffinate layer to a greater extent than the ketones andaldehydes were removed.

35 ml. of the' above raffinate (before water washing) was shaken with 35ml. of gamma-butyrolactone at 25 C. to demonstrate the effect of a twostage extraction. The rafiinate volume was 31 ml., and the extractvolume was 39 ml. The rafiinate layer was washed with water, dried, andanalyzed. It was found that 67.5% of the alcohol in the first ratfinatehad been removed and that 33.6% of the oxygen-containing hydrocarbonshad been removed. In the two stage extraction process, 91.5% of thealcohols had been removed from the initial charge stock and 67.8% of theoxygen-containing hydrocarbons had been removed. It is evident thatexcellent separations of oil-soluble, water'immiscible alcohols fromnormally liquid hydrocarbons can be made by the invention hereindisclosed.

Thus having described the invention what is claimed is:

1. A method for refining a mixture comprising normally liquidhydrocarbons and oil-soluble water-immiscible alcohols, which processcomprises selectively extracting said mixture with liquidgamma-butyrolactone, and separating a liquid extract phase.

2. The method of claim 1 wherein the hydrocarbonalcohol solution is notreadily separable by distillation.

3. The method of claim 1 wherein the mixture which is extracted withsaid liquid gamma-butyrolactone is produced by hydrogcnating carbonmonoxide in the presence of an iron catalyst and thereby producingwater-soluble oxygenated organic compounds, water-immiscible oilsolubleoxygenated organic compounds and hydrocarbons, recovering a mixture ofhydrocarbons containing dissolved water-immiscible oil-soluble organicoxygenated compounds comprised of carboxylic acids, alcohols, aldehydesand ketones, removing carboxylic acids from the mixture of hydrocarbonsand dissolved oil-soluble organic oxygenated compounds, and thereafterextracting with liquid gamma-butyrolactone the mixture of hydrocarbonsand organic oxygenated compounds from which carboxylic acids had beenremoved.

4. The method of claim 1 wherein the mixture of hydrocarbons andalcohols contains aldehydes, and where said mixture is hydrogenated toconvert aldehydes to alcohols, and is thereafter extracted with liquidgammabutyrolactone.

5. A method for refining a mixture comprising normally liquidhydrocarbons and water-immiscible alcohols and organic carbonylcompounds which process comprises contacting said mixture with an amountof liquid butyrolactone sufiicient to form distinct extract and ran?-nate phases, washing said extract phase with normally liquid"hydrocarbons and thereby scrubbing organic carbonyl compounds from saidextract phase, and recovering a scrubbed extract phase ofgamma-butyrolactone rich in alcohol.

6'; The method of claim 5 wherein the liquid hydrocarbon employed inscrubbing the extract phase boils References Cited in the file of thispatent UNITED STATES PATENTS 2,059,495 Smeykal Nov. 3, 1936 2,205,184Woodhouse June 18, 1940 2,543,038 McGrath Feb. 27, 1951 6 1 Hess et a1June 26, 1951 Arnold et a1 Sept. 25, 1951 Michael Oct. 28, 1952 KaufmanDec. 30, 1952 Michael Jan; 13, 1953 Nelson Apr. 22,1958 I Bieber et alAug. 5, 1958

1. A METHOD FOR REFINING A MIXTURE COMPRISING NORMALLY LIQUIDHYDROCARBONS AND OIL-SOLUBLE WATER-IMMISCIBLE ALCOHOLS, WHICH PROCESSCOMPRISES SELECTIVELY EXTRACTING SAID MIXTURE WITH LIQUIDGAMMA-BUTYROLACTONE, AND SEPARATING A LIQUID EXTRACT PHASE.